1. Field of the Invention
This invention relates to a stroller, more particularly to a stroller with an adjustable backrest.
2. Description of the Related Art
FIGS. 1 and 2 illustrate a conventional stroller 1 that includes a leg unit with front and rear legs 111, 112, a seat frame 113 pivoted to the front and rear legs 111, 112, a backrest 12 with left and right backrest rods 121 pivoted to the seat frame 113, and a positioning unit. The positioning unit includes a pair of engaging pins 131 and a pair of positioning bases 13, each of which is pivoted to a respective one of the rear legs 112, and each of which is formed with a plurality of engaging grooves 135. Each of the engaging pins 131 projects from a respective one of the left and right backrest rods 121 to engage releasably a selected one of the engaging grooves 135 in a respective one of the positioning bases 13. Each of the positioning bases 13 is rotatable upwardly and downwardly between an engaging position, in which the respective engaging pin 131 engages the selected one of the engaging grooves 135, and a disengaging position, in which the respective engaging pin 131 disengages from the selected one of the engaging grooves 135. A releasing member 14 includes a pair of pushing members 146, each of which is mounted slidably on a respective one of the left and right backrest rods 121, and each of which contacts a bottom side of a respective one of the positioning bases 13, a pair of urging members 145, each of which is mounted in a respective one of the left and right backrest rods 121 above a respective one of the pushing members 146 and each of which is connected to the respective one of the pushing members 146, and a handle 141 with a string 143 connected to the pushing members 146 in such a manner that pulling of the handle 141 results in upward movement of the pushing members 146 against urging action of the urging members 145, which, in turn, results in upward movement of the positioning bases 13 to the disengaging position, thereby permitting adjustment of the backrest 12 to a desired position. Each positioning base 13 is restored to the engaging position by virtue of gravity upon being released from the pulling action of the handle 141.
The conventional stroller 1 is disadvantageous in that, since each positioning base 13 is simply laid on the respective engaging pin 131 at the engaging position by gravity, there is a tendency for the positioning base 13 to disengage undesirably from the respective engaging pin 131. Moreover, it is relatively inconvenient and laborious to assemble the releasing member 14. In addition, since each pushing member 146 is connected to a pin extending through a respective one of the let and right backrest rods 121, an elongated sliding slot (not shown) is required to formed in the let and right backrest rods 121 for passage of the pin when the pin is slid together with the respective pushing member 146, which results in decreasing in the mechanical strength of the let and right backrest rods 121. Furthermore, since each pushing member 146 is cylindrical in shape and has an annular sliding contact face that is in sliding contact with the respective one of the let and right backrest rods 121, sliding movement of the same on the respective one of the let and right backrest rods 121 during folding of the stroller is not smooth.